HA. H. Howorth—A Great Post-Glacial Flood. 360 
known as Sir W. Logan) had called his attention to the occurrence 
of chalk flints in drifted gravel near Cardigan, over a space of 
24 square miles. Some of the mounds of gravel being from 80 to 
100 feet high. Mr. Logan attributed the origin of these chalk flints 
to a current from the north (Proceedings Geol. Soc. vol. ili. p. 584, 
note). It seems clear that the spreading of the mantle of gravel and 
sand over the slopes where it occurs is most manifestly the work of 
water, while the distant origin of much of the material and its con- 
fused arrangement point as unmistakeably to violent rushes of water. 
Let us pass on. 
The high-level drifts either with shells or without, to which 
we have referred, are not covered by clay, but nevertheless they 
are unmistakeably the equivalents of the similar beds so covered 
in the plains of Lancashire and Cheshire and elsewhere, that is, of 
the so-called Middle Sands and Gravels. This is so obvious that it 
is not worth while enlarging upon it. Here, as on many other 
occasions, Mr. Mackintosh has done yeoman’s service (see GEOLOGI- 
caAL Macazinn, Vol. IX. pp. 189 and 190), but he is not alone. 
The so-called Middle Sands and Gravels are typically developed 
at Blackpool, in Lancashire; and, as Mr. Mellard Reade has shown, 
these shells are precisely those of the High Level Drifts; so are 
they in all other respects, and the same arguments as to their 
distribution apply to them. As in the case of the High Level Drifts, 
these lower gravels and sands of Lancashire pass, as we leave the 
sea-board, from a fossiliferous to an unfossiliferous condition, retain- 
ing their other characteristics intact. No one has ever doubted the 
precise equivalence of the two sets of beds. Mr. Binney, who knew 
these beds exceedingly well, wrote an interesting paper in the 
Memoirs of the Literary and Philosophical Society of Manchester 
(2nd series, vol. x. p. 121, etc.), in which he refers to some of the 
beds containing shells and others not, but it never enters his head 
to distinguish between their ages. Thus he says :—“ The difference 
in the distribution of organic remains in the Drift is a subject well 
worthy of attention. It does not appear.to be owing to the mechanical 
_ characters of the deposit ; for while no shells have been met with in 
the sands and fine gravels of Kersal Moor, near Manchester, similar 
deposits at Bowdon afford them in considerable abundance. The 
Till of Manchester, so far as it has at present been examined, is also 
destitute of fossil shells, while the same deposit in most places west 
of a line drawn from Preston to Runcorn yields them more or less. 
We should scarcely expect to find delicate and fragile shells in a 
coarse gravel. If the mechanical characters of the deposit would 
account for the difference in preservation of the organic remains, 
the matter would be comparatively easy ; but as we find that the 
sandy, gravelly and clayey strata of the deposits have little to do 
with the occurrence of the fossils, probably the beds on and near 
the flanks of the Pennine Chain may have been formed under con- 
ditions in some way less favourable-to organic life, or else the shells 
of the mollusks of the then existing shells have been more frequently 
destroyed than those deposits more remote and lying near the 
